Dc cooking appliance

ABSTRACT

A DC powered cooking appliance which uses an induction or a resistance based DC heating element and excludes AC powered heating elements and preferably does not rely on directly connected combustion powered heating elements. Some embodiments include wattage of 1500 watts or less, voltages of 40 or 48 volts or more and are installed on a boat, van, rv or bus such that an inverter of that boat, van, rv or bus is not electrically connected to the cooking appliance.

FIELD OF THE INVENTION

The following relates to a cooking appliance, more particularly a directcurrent (DC) cooking appliance such as a grill, cooktop, hot plate andthe like.

BACKGROUND OF THE INVENTION

Electric cooking appliances come in many shapes, sizes and types, butsince cooking often requires a large amount of heat and thus wattage, DChas typically been seen as an undesirable power source as it oftenrequires too high of an amperage to obtain acceptable heating.Alternating current (AC) has been more prevalent, typically becausehomes are powered by AC and because the current requirements are muchlower since the voltage is typically higher in AC as opposed to DC.

However, AC cooking appliances become a burden in certain situationswhere AC is not the primary power source available. For example, marinevessels often will have an alternator to supply power off the engine andthis will often come out as DC power. To power currently available ACcooking appliances in a marine vessel kitchen requires an inverter toconvert the DC to AC.

Some combined AC and DC grills have been theorized such as CanadianPatent 2,292,674 which describes the combined use of both DC and ACpower in that a battery is supplied which charges when the cookingappliance is off and then when turned on, the AC power supplies thefirst 1800 watts and the DC battery and heating element suppliesadditional wattage to obtain a combined power rating above 1800 wattswithout drawing more than 15 amps. The primary goal of that invention isto use DC to obtain extra heating, not to be the primary (and only) heatsource.

SUMMARY OF THE INVENTION

Therefore, it is an object of the present invention to provide a cookingappliance which uses DC powered heating elements as its primary heatsource, without use of AC heating elements, preferably a DC only poweredgrill.

It is further an object of the present invention to provide a DC poweredcooking appliance which is suitable for marine vessels, RVs, off-gridstructures and other locations to avoid/eliminate the need for aninverter or DC to AC converter.

It is further an object of the present invention to provide a DC cookingappliance which can be powered by high voltage DC batteries.

These and other objects are achieved by providing a cooking appliancecomprising a controller and a direct current (DC) powered heatingelement wherein the controller and heating element are configured toconnect to a source of DC electrical potential. Activation of the DCpowered heating element by the controller is configured to heat acooking surface which is configured to be located adjacent the DCpowered heating element to heat the cooking surface. The cookingappliance excludes an alternating current (AC) powered heating elementand excludes a combustion heating element.

In certain aspects the heating element is an induction DC poweredheating element and further comprising a support configured to support acooking vessel comprising the cooking surface and activation of the DCpowered heating element by the controller heats the cooking surface. Inother aspects the heating element is a resistance DC powered heatingelement. In other aspects the cooking appliance is configured to operateat 1500 watts or less. In still other aspects the DC powered heatingelement is connected to a source of DC potential of 30 volts or more 35volts or more or more preferably 40 volts or more. In still otheraspects the cooking appliance is configured to operate without activelydrawing power from a combustion activated DC power source.

In still other aspects a vehicle includes the cooking applianceinstalled on or in the vehicle. In still other aspects the vehicle isbattery powered electric vehicle and the cooking appliance is connectedto a battery of the vehicle. In yet other aspects the battery of thevehicle further powers one or more electric motors which cause thevehicle to move and the vehicle is a land, sea or air vehicle. In stillother aspects the cooking appliance has a wattage rating of 2000 W orless. In still other aspects the source of DC electrical potential isselected from the group consisting of: a battery, a solar panel, a windpowered generator. In yet other aspects the source of DC electricalpotential is configured to power the cooking appliance when the sourceof DC electrical potential does not receive power from an AC powersource.

In yet other aspects the cooking appliance draws less than 40 amps orless than 30 amps at a maximum power setting of the controller. In stillother aspects the cooking surface is a grill or griddle and wherein at amaximum power setting of the controller, the cooking appliance drawsless than 40 amps and generates heat sufficient to raise a temperatureof the grill surface to 500 deg within 10 minutes with a grill lidclosed and the cooking appliance positioned in a 70 deg F. environment.In still other aspects the cooking appliance has a wattage rating of1600 W or less or 1400 W or less.

In still other aspects the appliance includes a device which steps downvoltage positioned electrically between the controller and the source ofDC electrical potential such that the controller and the heating elementoperate at different voltages with the controller operating at a lowerDC voltage than the heating element. In still other aspects the heatingelement operates at a voltage which is at least 7 times the voltage ofthe controller.

Other objects are achieved by a cooking appliance having a controllerand a direct current (DC) powered heating element wherein the controllerand heating element are configured to connect to a source of DCelectrical potential. Activation of the DC powered heating element bythe controller heats a cooking surface configured to be located adjacentthe DC powered heating element. The cooking appliance excludes analternating current (AC) powered heating element.

In other aspects the source of DC electrical potential is connectedwithout an inverter or other DC to AC conversion device positionedelectrically between the source of DC electrical potential and the DCpowered heating element.

In still other aspects, a cooking appliance is provided with a heatingelement and a controller electrically connected to the heating element.The controller includes a conversion device which modifies power output,wherein the controller is configured to connect directly to a source ofDC electrical potential to modify power output to the heating element.Activation of the heating element by the controller is configured toheat a cooking surface which is configured to be located adjacent theheating element heats the cooking surface. The cooking applianceexcludes a combustion heating element.

In certain aspects the controller is a pulse width modulation (PWM)controller. In other aspects the PWM controller converts the DC input toa waveform of varied pulse widths of both positive and negative voltageto the heating element.

In other aspects a vehicle with a cooking appliance is provided. Thevehicle has a source of DC electrical potential. The cooking appliancehas a heating element; and a controller electrically connected to theheating element, the controller controlling power output to the heatingelement; wherein activation of the heating element by the controller isconfigured to draw electricity from the source of DC electricalpotential to generate heat; wherein the cooking appliance excludes acombustion heating element. The cooking appliance is connected to thesource of DC electrical potential without an DC to AC conversion devicepositioned electrically between the source of DC electrical potentialand cooking appliance. In some embodiments, the cooking appliance iscontained in a housing and no DC to AC conversion devices are positionedelectrically between the housing and the DC source.

In certain aspects the DC powered heating element is a DC poweredinduction heating element.

Other objects of the invention and its particular features andadvantages will become more apparent from consideration of the followingdrawings and accompanying detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B are a functional diagrams showing a DC grill.

FIGS. 1C and 1D are functional diagrams showing a DC cooktop.

FIG. 2 shows the DC appliance of any of FIGS. 1A-D installed in avessel.

FIG. 3 shows an exemplary wiring diagram for a DC grill according toFIGS. 1A and B.

FIG. 4 shows a perspective partial cutaway view of the grill of FIGS. 1Aand B.

FIG. 5 shows a detail view of FIG. 4 .

FIG. 6 shows an example control process implemented by the DC cookingappliance of the prior figures.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to the drawings, wherein like reference numerals designatecorresponding structure throughout the views. The following examples arepresented to further illustrate and explain the present invention andshould not be taken as limiting in any regard.

FIGS. 1A-B show a DC powered grill. The cooking surface 18 in this caseis a grill grate with a number of holes therein which allow matter topass therethrough into a drip pan below. The housing 16 includes acover/lid to close to retain more heat. The DC powered heat element 2.The grill grate 18 may be of the type disclosed in U.S. Pat. No.10,349,776, the contents of which are incorporated by reference herein.As can be seen in each of FIGS. 1A-D, the DC heat element 2 is the onlyheat element for the cooking appliance and AC heat elements are excludedas are inverters to convert DC to AC to power the controller. It iscontemplated that the Battery 6 may be charged by a charger 8 which maybe connected to AC power. It is also contemplated that the charger 8 mayconvert AC power to DC to act as a power supply for the controller 4 andthe DC heat element 2. In this manner when a vessel 100 (FIG. 2 ) isdocked, it can be connected to shore power which is typically suppliedas AC power. The same can hold true for use of the DC cooking appliancein other mobile units such as RVs, food trucks. It is furthercontemplated that an off grid home can have solar panels which supplyelectricity to the charger 8 which in turn charges the battery 6 whilethe controller 4 draws power from the battery 6 to power the DC heatelement 2. In any case, the DC cooking appliance is powered by DC andthus removes the need for an inverter.

Preferably the DC heat element 2 accepts a DC power source, preferredpower sources are 40v or greater, more preferably a 48v or greater, evenmore preferably 50v or more, 60v or more, 70v or more, or even 100v ormore DC sources. However, it is contemplated that lower voltages of e.g.12v, 24v or others may be useful. Particularly, the battery 6 may supplythese voltages. The controller may be a simple manual knob control or amore complicated electronic display or capacitive touch sensitivecontrol such as the one disclosed in U.S. Pat. No. 10,349,776. It iscontemplated that the controller may operate on voltages less than theDC power source. For example, 6v, 12v or 24v may be used to power thecontroller whereas the DC heat element 2 may use the higher voltage.This can be accomplished by a converter in the controller 4 which stepsdown the voltage as necessary. The controller 4 may also operate on thesame voltage as the DC power source.

In FIGS. 1B and 1D shows the embodiment most typically relevant in thesituation of a marine vessel, rv or other situation where a combustionmotor 14 is available. Particularly, an alternator 12 is connected tothe motor 14 by a drive shaft, gear or other device which transmits therotation and torque of the motor to the alternator 12. This alternatoris then connected to a voltage regulator 10 which ensures the requiredvoltage is output in DC. This DC voltage may be supplied to a charger 8which charges battery 6. The DC voltage from the regulator 10 may alsodirectly connect to the cooking appliance via the controller 4. Thus,although the cooking appliance may use AC power to charge the battery,ultimately an inverter is not needed and the heat element 2 is DCpowered and when AC power is not available, DC power may be suppliedfrom the alternator 12 and/or battery 6.

FIGS. 1C-D show an embodiment where the DC heat element 2 is a DCinduction coil and a pan/cooking vessel 18′ provides the cookingsurface. The housing 16 may include a glass top support surface underthe pan 18′. FIGS. 1A-B show an embodiment where the DC heat element 2is a DC resistance heat element. The DC heat element 2 in preferredembodiments provides less than 1800 watts of heating, more preferablyless than 1500 watts and even more preferably less than 1400 watts. Themaximum current draw of the appliance is preferably less than 35 amps,more preferably less than 30 amps, even more preferably less than 25amps and most preferably 20 amps or less. Higher than 1800 watts arecontemplated, typically with higher DC voltages of 48v or above asdiscussed herein. In certain cases 2000 watts or 2500 watts or more canbe used with appropriate battery voltages while keeping current atreasonably low levels—below 60 amps.

FIG. 2 shows an example of the DC cooking appliance with the DC heatelement 2 in its housing 16 which may be a grill housing, an inductioncooktop housing, an oven housing and others. Preferably the grill/ovenembodiments use resistance based heating coils. The battery bank 200comprised of multiple batteries 6 may power other appliances on thevessel such as radar, control systems, lighting etc. It is furthercontemplated that an all electric vessel may be provided which usesbattery power to propel the vessel 100. The cooking appliance may alsobe in an RV, van, off-grid home or other self-contained/self-poweredunit which may be battery powered, a hybrid battery/combustion power orcombustion powered. However, since the cooking appliance is DC powered,there is no need to convert from DC to AC with an inverter, rather thebattery bank can power the cooking appliance or an alternator can powerthe cooking appliance.

Although a battery is shown as the DC power source in FIGS. 1-2 , otherDC power sources are contemplated. FIG. 3 shows more details on thewiring of FIGS. 1A-B with a DC power source 6′ which may beapproximately e.g. 48v. This may be from an alternator on avessel/vehicle, a battery, solar, wind or other DC power sources. Inpreferred embodiments, the DC power source is not powered directly bycombustion. A solid state relay 24 is provided and controlled bycontroller 4 and circuit board 26. The controller pad 40 as shown isconnected via a CAT5 (e.g. ethernet) cable to the circuit board 26 toregulate the voltage output to the heat element 2 which is shown as aresistance based heating element. A DC fan 20 is also provided in orderto cool the controller pad 40 and circuit board 26. In preferredembodiments the voltage of the controller pad 40 and circuit board 26and DC fan 20 are all below 6v, preferably 3v or 5v. It is alsocontemplated that other controller variations may be used and thatcontroller 4 may be a more simple PWM (pulse width modulation)controller that uses a variable resistor to control the width of pulses.Thus, the controller may be selected from e.g. a number of conversiondevices which modify average power output from a DC source. That outputmay be in the form of a square wave (all positive) or an alternatingsquare wave with both positive and negative voltages output to theheating element, a smoothed DC output (e.g. a PWM usingcapacitor/resistor/induction devices to smooth the output) along with avariety of other conversion and control devices which can modify the DCinput to the cooking appliance to control the power output to theheating element.

In certain embodiments as shown in FIG. 6 , the controller 26 utilizes afeedback loop with the temperature sensor 28 to turn the relay on oroff, depending if heat is needed or not. Although a solid state relay isshown, other types of contactors can be used to switch current/voltageon/off when needed.

When the keypad 40 instructs the controller 26 to turn on the cookingappliance 100, the solid state relay 24 will open and allow current toflow through the heating element. The embodiment of FIG. 3 shows aresistance heat element. The solid state relay is one example of a fieldeffect transistor (FET) which can be used to turn on/off power to theheating element. It is understood that various other types of FETdevices can be used as these are effective at switching on/off power atrelatively high current values (e.g. above 15 A, above 20 A, above 25 Aetc). In contrast, mechanical switches would require significant heatdissipation capabilities in order to switch the level of current of a DCbattery/power source in the scenario of a cooking appliance and giventhe PWM controller and the frequency of switching, this may rendermechanical switches unsuitable in DC cooking applications.

It is understood that a more simple dial system can be used inconnection with PWM controller which uses a knob instead of a capacitivetouch screen as found in the keypad 40. In either case, the amount ofheat requested whether by turning a knob or by a signal from the keypad40, will be indicative of a temperature. Thus, a heat setting of 7 outof 10 on a potentiometer would indicate a particular temperature. Incertain embodiments, they keypad 40 can actually display a temperatureand allow that temperature to be selected by the user. With this heatsetting 102 in mind, a temperature reading 104 is taken. The controller26 compares the setting to the reading. If the temperature is not lowerthan the setting, the relay closes (or remains closed) 108. If thereading is lower than the setting, the controller determines how closethe reading is to the setting temperature. A threshold may be set as apercentage or degree differential or other, but this threshold isdesigned to take into account that when the heating element is turnedoff (relay closed), the temperature reading on the sensor 28 willcontinue to rise, thus the threshold is designed to avoid overshoot.Setting 102 may be indicative of a range, thus if the reading is outsidethe range, this would indicate the relay needs to open unless thedifference is within the threshold 110. If the reading is too low oroutside the range, specifically below the range, this would cause therelay to open 112 (or stay open). The solid state relay is in someembodiments important to the operation of a DC cooking appliance.Specifically, DC power of a cooking appliance will operate at arelatively high current compared to a similar sized AC appliance. As aresult, a more simple potentiometer circuit may not be possible due tohigh current requirements. Instead, controlling a solid state relay toturn on or off depending on the temperature reading as compared to thesetting is significantly more effective and efficient and also would notgenerally be desirable in AC cooking appliances such as grills andcooktops.

Furthermore, since a pulse width modulation (PWM) controller is used, itis understood that the solid state relay may pulse on/off frequently toin effect provide a lower average voltage to the heating element andthus less power. However, one key difference between AC and DC grills isthat AC grill have the ability to switch a mechanical relay when the ACvoltage is at or near zero, specifically the PWM controller of an ACgrill will time the pulses with the zero point of the AC waveform. But,the solid state relay is provided in that the DC power source does nothave these same oscillations that allow for taking advantage of zerovoltage for switching. Thus, the SSR 24 will switch at non-zerovoltages, typically voltages that are the same or close to inputvoltages, or at minimum 50% or more of input voltages. By switching atsubstantially non-zero voltage, this is different than switching of ACvoltages which although very fast at e.g. 60 Hz, is not substantiallyinstantaneous as the sinusoidal waveform of AC can be advantageouslyused to switch a mechanical relay on and off when the voltage is atsubstantially zero in the oscillation cycle. Thus, in the DC switchingthe voltage is immediately delivered as is a relatively high amount ofcurrent. Essentially, when the relay is opened to allow delivery ofvoltage, substantially the only restriction on the heat elementreceiving that 48 volts is the internal resistance of the wires and thespeed at which electricity travels. In contrast, an AC relay switched atsubstantially zero voltage would not immediately cause voltage to bedelivered to the heat element as the AC line in would need to climb involtage according to the sin wave shape. The pulses controlled by thePWM controller provides a substantially square for voltage or squarewaveform voltage input whose width and period may vary depending on theheat required. The non-zero switching results in substantially immediatedelivery of full voltage and associated current to the heat element.With a DC source, there is a substantially constant voltage deliveredwhich means high current rates and challenging temperatureconsiderations. This substantially constant voltage does contemplateminor variations that can occur upon initial startup for e.g a voltageregulator of an alternator to react to the call for voltage, but at thesame time, the voltage does not drop to a substantially non-zero voltageto allow switching in accordance with a sin wave.

The solid state relay is able to handle these high current and voltageswitching operations that AC grill controllers and their associatedrelays would not handle effectively. As stated earlier, AC controllerswill take advantage of the zero or substantially zero periods of voltageto time the switching of a mechanical relay in order to have theswitching occur at lower voltages and currents.

In the DC scenario and as shown in FIG. 3 , the controller (40/26)connects to the 4/A2 and 3/A1+ inputs on the solid state relay 24. Thiseither provides or does not provide voltage to the relay. If voltage isprovided, the relay is on and power is supplied to the heating element2. If no voltage is provided to terminals 4/A2 and 3/A1+, the solidstate relay remains off. The voltage delivered to terminals 4/A2 and3/A1+ is typically around 5v. Terminals −2 and +1 are those that areswitched/connected by operation of the relay to either deliver or notdeliver the incoming voltage 6′ to the heat element 2. This switchinglogic is controlled based on inputs from the temperature sensor 22 whichcontacts the grill grate/griddle, typically the underside thereof or areotherwise in a position to measure temperature of the cooking appliance,typically positioned below the cooking surface and spaced away fromholes e.g. a grill grate to avoid the temperature sensor becomingcovered in grease/drippings. Temperature readings are used by thecontroller to determine when to turn on voltage to the heat element 2,specifically the circuit board 26 which receives control inputs from thekeypad 40, which in connection with the temperature sensor 22, are usedto control the temperature of the grill. In preferred embodiments, thesensor 22 is in contact with the grill grate in a location spaced fromholes which allow matter to pass there through (such as grease) as shownin FIGS. 4 and 5 , alternately, the sensor 22 can be below the grate butnot in contact or otherwise infer temperature from something in contactwith the grate or the element which includes the cooking surface. Theglass temperature sensor 28 is used to turn the fan 20 on and off, thissensor 28 reads the temperature of the glass that the keypad 40 is partof and the fan 20 is used to ensure the controls are not too hot totouch and that they are also protected from heat damage.

It is understood that the voltages refer to industry standards in termsof how voltages are identified in that a 3v does not necessarily operateon precisely 3.0v as there is a known range in the industry ofapplicable voltages when a 3v controller (or 5v controller) isidentified. For example 3v is sometimes referred to as 3.3v. The sameapplies to the DC power supply in general. For example, a 48v supply mayrefer to a range or slightly different voltage due to battery chemistryor the configuration of the solar panel array such that the input is notprecisely 48.0v. These voltages are exemplary only and not limited.

Also connected to the circuit board is a temperature sensor (e.g. anResistance Thermal Detector or RTD) which is in contact with the grillgrate/griddle on the bottom thereof in order to measure the temperaturethereof. That temperature may be used to regulate the heat output to theheat element 2 such that the user can set a temperature and thecontroller will maintain the cooking surface at that temperature basedon the readings from the RTD. The control pad 40 and circuit board 26operate as the controller 4 in order to allow for selection of heatsettings and in order to regulate the DC output to the heating element2. Often, the controller 4 will regulate the voltage output to theheating element 2 such that at e.g. the full 48v, approximately 1300 wis produced whereas when the controller reduces the voltage coming outof the SSR 24 at the connector labeled −2, the wattage output will belower.

Therefore, in certain embodiments, the controller and SSD can bothprovide a step down voltage to allow the controller to operate at lowervoltages (e.g. 3v or 5v) and then allow the heating element to operateup to the voltage of the power supply. In preferred embodiments, theinput voltage which can be applied to the heating element is at least 5times that of the controller voltage, more preferably at least 6 times,at least 7 times or at least 8, 9 or 10 times or more the voltage.

Referring to FIGS. 4 and 5 , the complete grill is shown with a partialcutaway of the grate 18 shown detail at FIG. 5 . The grill housing 16 isprovided with a lid 50 and a base housing 64. The lid is hinged 54 toallow for opening/closing and to retain heat. The RTD 22 extends fromthe opening 52 in the grill that receives the grate 18, specificallyfrom the rear edge 56. The heating element 2 is also shown connected tothe rear edge 56 which is part of the rectilinear opening of the grillthat houses the grate 18 or griddle and heating element 2. The RTD 22sits in a channel within the lower portion of the grate 18 to measurethe grate temperature. The control pad 40 is provided to allow the userto regulate the heat in the two different zones shown. It is furthercontemplated that a single zone control pad may be provided and a singlezone for the grill, thus making the grill smaller than what is shown inFIG. 4 , essentially, having only one of the two zones shown in FIG. 4 .A DC grill in a smaller size may be particularly useful for camping,boating, mounting in vehicles or other scenarios where portabilityand/or space savings are important. The DC grill may be powered byrechargeable battery packs similar to power tool batteries which can beeasily released and recharged and re-used. It is also contemplated thatthe grill may be provided with a connector which can plug intocommercially available portable battery banks, e.g. with a cigarettelighter style plug or through other user releasable connectors similarto how power tool batteries are connected to tools. These batteries mayinclude e.g. 20 v or more, 24 v or more, 28v or more, 36v or more, 40vor more, 48v or more, 56v or more, 60v or more, 80v or more. However,higher voltage batteries may be used in combination with a step downconverter. For example, electric vehicles often have batteries withvoltages of 300v or more, e.g. 315v, 375v and higher. In situationswhere the cooking appliance is powered by one of these batteries, it maybe beneficial to utilize a step down voltage converter to use lowervoltages. Alternately, a higher voltage rated heating element may beused with a controller configured to control higher ranges of voltagesand the voltage multiple of the maximum input for the heating elementrelative to the controller may be upwards of 50, 55, 60, 65, 70 or more.The control pad 40 and circuit board 26 will usually operate on lowervoltages below 28v, below 12v or below 6v (e.g. 3v or 5v). A shown inthe wiring diagram, the incoming voltage of the power source 6′ may bean input for the circuit board 26 as a reference voltage so that thecontroller 4 is able to determine what voltage it is starting with sothat the correct step down can be implemented and so that the controllerknows what the input voltage is so that power output can be controlled.

FIG. 6 shows that when the grill is turned on 100, a heat setting 102 isobtained. This heat setting 102 may be a specific temperature or may beindicative of a temperature based on a range setting, such as 1-10 onthe control pad or low/medium/high or others. Once the user sets thecontrol knob/control panel, the temperature reading 104 is used todetermine if heat needs to be added. When the reading is not lower thanthe setting (or is not below the range) 106, the relay is closed or doesnot open 108. However, if the temperature reading is lower than thedesired temperature based on the controller setting, the controllerdetermines how far away from the desired temperature. For example, thecontroller may maintain the actual temperature within a range of +/−10deg. F. relative to the desired temperature. If outside this thresholdrange (specifically below the range), the relay will open/pulse 112. Thewidth of the pulses may be controlled based on how far away from thedesired temperature the reading is. Particularly, when the appliance isfirst turned on, the temperature will read relatively cool in comparisonto the desired temperature. At this point, the pulses will be wide orpotentially the relay will simply be opened in order to reach thedesired temperature as fast as possible. The temperature reading 104acts as a feedback loop so that as the temperature increases, the relaycan be pulsed open at narrower widths in order to avoid overshooting thedesired temperature, then once the desired temperature is reached, thecontroller will cause the relay to pulse at relatively narrow widths.However, once cold food items to be cooked are placed on the grill, thetemperature may begin to drop rapidly at which point the relay would beopen entirely or open at wider pulse widths to quickly return to thedesired temperature. In each case when the relay is opening/closing orpulsing, this is done at non-zero voltages, more particularly at theincoming line voltage 6′ which is the DC voltage from e.g. a 48v batteryor other battery or DC power source.

In some preferred embodiments, the grill may be able to operate withoutbeing connected to a combustion powered unit, for example, in avessel/car without the engine running and using only battery power butthat the vessel/car may include an alternator/charger feature whichcharges the battery for the grill when not in use and then allows thegrill to operate without the engine running and thus not creating adirect connection to active combustion power. In this manner, the grillcan be used normally without running an engine or a generator,preferably by drawing from a battery, solar panel, wind generator orother similar DC power source which does not require active combustion,e.g. so that it can operate off grid and without a combustion generator.

In some embodiments, the grill may draw power directly from batteries inan electric vehicle or hybrid vehicle (which may include a vessel, car,van, RV, golf cart and the like) and the controller 4 may be furtherconnected to the vehicle battery controller to prevent draining thevehicle battery with the grill unintentionally or by alerting the uservia SMS or other electronic messaging or automatically shutting off thegrill to avoid drawing down the battery which is used to move thevehicle.

As described herein, the cooking appliance excludes AC powered heatingelements and further excludes combustion heating elements. For example,this would exclude gas, wood and charcoal burning capabilities,particularly excluding gas ignitors and nozzles along with the exclusionof various baskets and holders designed to hold burning/smokingwood/charcoal to heat the grill. Further, in some aspects there is noneed for any rectifier or equivalent, particularly between the sourcevoltage and the controller as the input is already DC. For example,rectifier circuits are characterized by a series of diodes which convertthe normally sinusoidal AC wave which has positive and negative peaks tothen only have either positive peaks or negative peaks. Next, acapacitor is provided to smooth these positive or negative peaks to be aconsistent voltage (or more consistent voltage). This is but one type ofrectifier circuits and equivalent circuits are known which can convertthe sinusoidal AC wave to a constant (or more constant) DC output. Thistype of circuit is therefore not required in an electric DC grillwhereas AC grills will typically be made with DC controllers and requirea rectifier or equivalent. The DC appliance has the benefit of using thesame type of power (DC in this instance) to both generate heat and tocontrol that heat generation.

In some aspects, the controller herein may be a pulse width modulation(PWM) controller which is used to drive the solid state relay and the DCheating coil on the grill. The PWM controller is considered another typeof step down voltage controller. However, it is understood that theactual voltage delivered during the “on” part of the pulses may benormal line or incoming battery/power supply voltage but by varying thewidth (time) of these pulses, the average voltage is lowered. In somecases, the output in pulses may be smoothed by a number of knowncircuits or circuit components, for example, use of capacitors is oneoption. Capacitors are often used in an AC to DC conversion in that theAC sin wave with negative and positive polarity is transformed by abridge diode circuit to just be positive (or just negative) and then thevalleys are smoothed out by a capacitor to deliver a more consistent DCvoltage. The PWM controller may be controlled by a variable resistanceknob or an integrated control in the driver circuit of the PWMcontroller. Thus, although a PWM controller may produce some alternationin that the voltage goes between 0 (between pulses) to the batteryvoltage during the pulses, this would not be considered AlternatingCurrent. Instead, AC relates to voltage that changes polarity during itswave form cycle. However, the PWM controller would still preferably bepowered by DC and may output an alternating voltage to the heatingelement as the heating element may be a resistor designed to dissipateheat whether DC (e.g. smooth, pulses or other forms) or pure AC (sinwave) or modified AC (e.g. alternating pulses). The PWM operates toreduce the average power distributed to the heating element by normallyproviding alternating pulses of power and no power to reduce the averagevoltage delivered to the heat element (and thereby reduce the averagepower). Current controllers can also be used to vary the powerdistributed to the heating element.

A at a maximum power setting of the controller, the cooking appliancegenerates heat sufficient to raise a temperature of the grill surface to500 deg within 10 minutes with a grill lid closed and the cookingappliance positioned in a 70 deg F. environment. Furthermore, thecooking element, such as the grill grate, defines a cooking area insquare inches and a wattage to area ratio is in the range 4.5-20 wattsper square inch, more particularly 5-18 watts/square inches more evenmore particularly 6-15 watts per square inch. In some preferredembodiments, the heat element delivers a maximum wattage in the range of800-2000 watts, particularly 1000-1800 watts, more particularly1100-1500 watts. It is contemplated that the cooking appliance couldhave multiple zones with each zone having the disclosed wattage ranges,voltages, currents and wattage to area ratios described herein. Forexample, FIG. 4 shows a two zone grill. In the preferred embodiment,each grate is about 150-170 square inches, more particularly 155-165square inches.

Although the invention has been described with reference to a particulararrangement of parts, features and the like, these are not intended toexhaust all possible arrangements or features, and indeed many othermodifications and variations will be ascertainable to those of skill inthe art.

What is claimed is:
 1. A cooking appliance configured to heat a cookingsurface comprising: a controller; a solid state relay electricallyconnected to and controlled by the controller; a direct current (DC)powered heating element electrically connected to the solid state relay;a source of DC electrical potential; wherein activation of the DCpowered heating element by the controller is caused by switching thesolid state relay on to deliver DC electrical potential from the sourceof DC electrical potential to the DC powered heating element to therebyheat the cooking surface which is configured to be located adjacent theDC powered heating element; wherein the cooking appliance excludes analternating current (AC) powered heating element and excludes acombustion heating element.
 2. The cooking appliance of claim 1 whereinthe controller is a pulse width modulation (PWM) controller whichcontrols switching the solid state relay on and off to deliver a squareform voltage to the DC powered heating element.
 3. The cooking applianceof claim 1 wherein switching the solid state relay on is accomplishedwhile the source of DC electrical potential delivers a substantiallynon-zero voltage.
 4. The cooking appliance of claim 3 wherein thesubstantially non-zero voltage is at least 30% of a voltage of thesource of DC electrical potential.
 5. The cooking appliance of claim 3wherein the substantially non-zero voltage is at least 24 volts.
 6. Thecooking appliance of claim 5 wherein the substantially non-zero voltageis at least 40 volts.
 7. The cooking appliance of claim 6 wherein thesubstantially non-zero voltage is at least 48 volts.
 8. The cookingappliance of claim 1 wherein the cooking surface has an area and theheating element and source of DC potential deliver a maximum wattage andwherein a ratio of the maximum wattage to area is 5-15 watts/squareinch.
 9. The cooking appliance of claim 1 further comprising atemperature sensor configured to read a temperature indicative of acooking area temperature of the cooking appliance and the controller isconfigured to be set with a setting indicative of a desired temperaturewherein the controller compares the setting with the cooking areatemperature read by the temperature sensor and turns the relay on or offbased on that comparison to maintain the desired temperature indicatedby the setting.
 10. The cooking appliance of claim 9 wherein the settingindicative of a temperature is indicative of a range of temperatures.11. A cooking appliance configured to heat a cooking surface comprising:a controller; a contactor electrically connected to and controlled bythe controller; a direct current (DC) powered heating elementelectrically connected to the contactor; a source of DC electricalpotential having a voltage; wherein activation of the DC powered heatingelement by the controller is caused by switching the contactor on whenthe voltage is substantially non-zero and the switching substantiallyimmediately delivers the DC electrical potential to the DC poweredheating element to heat the cooking surface which is configured to belocated adjacent the DC powered heating element.
 12. The cookingappliance of claim 11 wherein the cooking appliance excludes analternating current (AC) powered heating element and excludes acombustion heating element.
 13. The cooking appliance of claim 11wherein the voltage is at least 40 volts and a maximum wattage rating ofthe cooking appliance is in a range of 800-1800 watts.
 14. The cookingappliance of claim 11 wherein the contactor is a field effect transistor(FET).
 15. The cooking appliance of claim 11 further comprising atemperature sensor which allows the controller to read a temperature ofthe cooking appliance and based on temperature readings from thetemperature sensor as compared to a setting indicative of a desiredtemperature, the controller switches the contactor on and off tomaintain the cooking appliance at the desired temperature.
 16. Thecooking appliance of claim 15 wherein the temperature sensor is incontact with a cooking element having the cooking surface thereon andthe controller maintains the cooking surface at substantially thedesired temperature.
 17. The cooking appliance of claim 11 furthercomprising: a vehicle including the cooking appliance installed on or inthe vehicle.
 18. The cooking appliance of claim 11 wherein the vehicleis battery powered electric vehicle and the cooking appliance isconnected to a battery of the vehicle.
 19. The cooking appliance ofclaim 11 wherein the contactor is a solid state relay and the controlleris a pulse width modulation (PWM) controller.
 20. The cooking applianceof claim 1 having a wattage rating of at least 800 W and 2000 W or less21. The cooking appliance of claim 11 wherein the cooking elementdefines a cooking area and the cooking area combined with the DC poweredheating element results in a cooking area to wattage ratio of at least4.5 watts per square inch and less than 20 watts per square inch.
 22. Acooking appliance configured to heat a cooking surface comprising: acontroller; a field effect transistor (FET) connected to and controlledby the controller; a direct current (DC) powered heating elementelectrically connected to the FET; a source of DC electrical potential;wherein activation of the DC powered heating element by the controlleris caused by switching the FET to deliver DC electrical potential fromthe source of DC electrical potential to the DC powered heating elementto thereby heat the cooking surface which is configured to be locatedadjacent the DC powered heating element; wherein the cooking applianceexcludes an alternating current (AC) powered heating element andexcludes a combustion heating element.